Read the product insert that came with the ligation kit. It is going to depend on the type of ligation (TOPO-TA clone vs. ligase) and the type of transformation (electrical or chemical).

Good luck!

If you don't purify the ligation reaction from a gel, what's possible is that transformation could yield colonies of self vector ligation and also vector with ligated insert. But surely one of the colonies of the transformation should yield correct plasmid with ligated insert assuming the primers and restriction enzymes you used were correct and efficient.

Hello,

Purification may depend on the processing method you are going to use.

Electroporation is more demanding in terms of purity (salt and protein) and for example the presence of salt can completely prevent the transformation from taking place by electroporation.

However, transformation by thermal shock (chemical transformation) is less demanding than electroporation, in terms of purity.

If using chemical transformation you can just use the ligation mix directly. To visualize a ligation on a gel requires large quantities of both vector and insert.

It is unlikely that you will see a distinct band that represents the plasmid + insert. There are numerous ligation products that result but those are often cleaned up after transformation to only the viable products. And as Robert Adolf Brinzer mentioned, you really need a lot of DNA to see the products.

Most just transform the ligation product directly along with controls of vector with and without ligation to know the background.

Hello , Laura Dionisi ,Before the ligation, you can purify both the vector and insert. I believe there is no need to run a gel after the ligation; you can proceed directly to the transformation. For confirmation, you can perform a positive control. I think that would be the easiest way.

Good luck

To add to what others have said, if you are doing chemical transformation, yes, you can skip the purification step (and skip a gel). If self-ligation of your vector is a concern, there are a few controls you can add.

1. cut vector with ligase added (no PCR/insert added), this will show how much of your vector was never cut and how much self-ligated

2. cut vector with no ligase added (no PCR/insert added), this will show now much of your vector was never cut

You set up these control reactions alongside your actual ligation, and transform them all in parallel as well. Ideally, your control reactions will give few colonies (usually the vector with ligase give a few more than the vector without), and you'll get the most colonies from your experimental ligation.

As a note, if your PCR product is from a vector and that vector has the same selective marker as your final vector then you'll want to do a gel and PCR cleanup of your PCR product for sure prior to ligations as you can get that initial vector coming through your transformation (not much, but it can be enough to show up).